As such an electronic apparatus, there is known a small-sized information processing apparatus including attitude detection means for detecting an attitude as described in, for example, Patent Document 1. In this small-sized information processing apparatus, when a scroll start switch as key operation means is depressed, a tilt angle (tilt angle with respect to the gravity direction) of the display unit at this point in time is detected by a tilt sensor as detection means. After this detection, the tilt angle of the display unit is detected again by the tilt sensor, and from the tilt angle detected at this time, the tilt angle at the time of depressing (basic attitude data) is subtracted, thereby a relative tilt angle from the angle at the time of depressing is calculated. Then, based on this relative tilt angle, the screen of the display unit is scrolled. More specifically, by this relative tilt angle, the relative tilt direction of the display unit from the time of depressing is recognized, and a process for scrolling the display screen toward a direction corresponding to the tilt direction is performed. A process for lowering the scrolling speed of the display screen is also performed when this relative tilt angle is less than a predetermined angle (motion identification data), and increasing the scrolling speed of the display screen when the angle is not less than the predetermined angle.
There is also known a mobile terminal having acceleration detection means for detecting acceleration as described in Patent Document 2. This mobile terminal includes means for determining whether acceleration generated when a user shakes this terminal is not less than a predetermined threshold value (motion identification data). In this Patent Document 2, a detailed example is described in which the number of times when the acceleration becomes not less than the predetermined threshold value is counted and a process for calling a phone number corresponding to the count is performed. The threshold value is a value set for distinguishing acceleration generated when a user shakes this terminal from a vibration applied when the user does not shake the terminal, for example, when the user uses a means of transportation. In the Patent Document 2, as a method for setting this threshold value, it is described that when the “FCN” key and “5” key as key operation means are depressed, the mode shifts to a mode of threshold value detection, and a value obtained by adding a maximum value of acceleration detected by the acceleration detection means in 24 hours with a value of several to 50 percent of the maximum value is used as the threshold value. This maximum value of acceleration detected in 24 hours is a maximum value of acceleration generated when the user does not shake the terminal. Therefore, by using a value obtained by adding a value of several to 50 percent of the maximum value as the threshold value, the acceleration generated when a user shakes the terminal can be distinctively recognized from the acceleration generated when the user does not shake the terminal.    Patent Document 1: Japanese Unexamined Patent Application Publication No. H07-64754    Patent Document 2: Japanese Unexamined Patent Application Publication No. 2002-330210
In the small-sized information processing apparatus of the Patent Document 1, a handling method when the attitude of the entire apparatus is changed so as to tilt the display unit differs among users. Therefore, as the predetermined angle that becomes a threshold value for determining fast or slow scrolling speed of the display screen, the respective angles most suitable for the respective users are used. However, in this small-sized information processing apparatus, the predetermined angle is fixed in advance regardless of the users. Therefore, a user has trouble in operating the apparatus if the fixed angle is not suitable for him/her.
In addition, in this small-sized information processing apparatus, when the scroll start switch is depressed, a tilt angle of the display unit at this point in time is detected to acquire basic attitude data, and at the same time, a process for scrolling the display screen of the display unit is started. In such a case where the basic attitude data acquisition timing and the start timing of the process using this basic attitude data are concurrent with each other, it becomes impossible to separately start a process using the basic attitude data after the basic attitude data is acquired. Therefore, for a user who does not want to use the attitude of the display unit at the start time of the process as the basic attitude, the basic attitude of the process is not the same as his/her desired basic attitude. As a result, operability for the process is deteriorated.
In addition, in the mobile terminal of Patent Document 2, the magnitude of the acceleration generated when a user shakes the mobile terminal changes depending on the shaking manner and the shaking force. The shaking manner and force differ among users. Accordingly, the optimum threshold value for distinguishing the acceleration generated when a user shakes the mobile terminal and acceleration generated when the user does not shake the mobile terminal is different among users. Therefore, when the threshold value set according to the threshold value setting method described in Patent Document 2, etc., so as to enable distinction between the acceleration generated when a user shakes the mobile terminal and the acceleration generated when the user does not shake is not suitable for the user, operability for the user is low.
The description given above concerns an example in which a process for changing a scrolling speed of a display screen and a process for calling a phone number are performed when the mobile terminal is moved so as to change in attitude or generate acceleration, however, the problem is not limited to these processes.
Accordingly, it would be desirable to provide an electronic apparatus which can improve operability when a specific process is executed by moving the electronic apparatus by shaking or tilting it by a user.